Not a conventional Bezier spline method, but can be useful for some applications.
;
; ALTERNATIVE CURVING CONSTRUCTION METHOD
;
; "how to get a curve using two lines segments"
;
; ralph.le.gall@...
Graphics 800,600,GraphicsDepth(),6
stp=20 ;<--you can change this "step" value
x1#=150 : y1#=150 ;A starting place coords
x2#=650 : y2#=450 ;B starting place coords
Dim xyA#(stp,1) ;"segments line steps"
Dim xyB#(stp,1) ;"segments line steps"
Dim xyZ#(stp,1) ;"segments curve steps"
;set green and yellow 3x3 dots..
dotAB=CreateImage(3,3) : SetBuffer ImageBuffer(dotAB) : ClsColor 0,120,0 : Cls : MidHandle dotAB
dotZ=CreateImage(3,3) : SetBuffer ImageBuffer(dotZ) : ClsColor 255,255,0 : Cls : MidHandle dotZ
SetBuffer BackBuffer()
ClsColor 0,0,0
MoveMouse x2#,y1# ;move mouse to "orthogonal" place
;__________________________________________________________________________________________________________________
While KeyDown(1)=False
xm#=MouseX() : ym#=MouseY()
Cls
;-------------------------------------------------------------------------------------------------
;INFOS
;-------------------------------------------------------------------------------------------------
Color 120,120,120
Text 10,10,"Left click = place A"
Text 10,25,"Right click = place B"
Text xyA#( 0,0),xyA#( 0,1),"A"
Text xyB#(stp,0),xyB#(stp,1),"B"
;-------------------------------------------------------------------------------------------------
;-------------------------------------------------------------------------------------------------
;SET SEGMENTED LINES AND CURVE
;-------------------------------------------------------------------------------------------------
;construction lines coords..
tmp_float#=(xm#-x1#)/stp : For i=0 To stp : xyA#(i,0)=x1#+((tmp_float#)*i) : Next
tmp_float#=(ym#-y1#)/stp : For i=0 To stp : xyA#(i,1)=y1#+((tmp_float#)*i) : Next
tmp_float#=(x2#-xm#)/stp : For i=0 To stp : xyB#(i,0)=xm#+((tmp_float#)*i) : Next
tmp_float#=(y2#-ym#)/stp : For i=0 To stp : xyB#(i,1)=ym#+((tmp_float#)*i) : Next
;curve coords (based on previous construction lines)..
For i=0 To stp
tmp_float#=(xyB#(i,0)-xyA#(i,0))/stp : xyZ#(i,0)=xyA#(i,0)+((tmp_float#)*i) ;X curve values
tmp_float#=(xyB#(i,1)-xyA#(i,1))/stp : xyZ#(i,1)=xyA#(i,1)+((tmp_float#)*i) ;Y curve values
Next
;-------------------------------------------------------------------------------------------------
;-------------------------------------------------------------------------------------------------
;VISUAL ELEMENTS
;-------------------------------------------------------------------------------------------------
;green segments lines..
Color 0,60,0 : For i=0 To stp : Line xyA#(i,0),xyA#(i,1),xyB#(i,0),xyB#(i,1) : Next
;green and yellow 3x3 dots..
For i=0 To stp
DrawImage dotAB,xyA#(i,0),xyA#(i,1) ;green dots (from A to mouse_XY)
DrawImage dotAB,xyB#(i,0),xyB#(i,1) ;green dots (from mouse_XY to B)
DrawImage dotZ, xyZ#(i,0),xyZ#(i,1) ;yellow dots
Next
;yellow segments curve..
Color 160,160,0 : For i=0 To stp-1 : Line xyZ#(i,0),xyZ#(i,1),xyZ#(i+1,0),xyZ#(i+1,1) : Next
;-------------------------------------------------------------------------------------------------
;-------------------------------------------------------------------------------------------------
;PLACING DOTS A B
;-------------------------------------------------------------------------------------------------
If MouseDown(1) Then x1#=xm# : y1#=ym#
If MouseDown(2) Then x2#=xm# : y2#=ym#
;-------------------------------------------------------------------------------------------------
Flip False
Wend
;__________________________________________________________________________________________________________________
End
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